.386
.model flat ,stdcall

NULL    equ 0
MB_OK   equ 0

ExitProcess PROTO :DWORD
MessageBoxA PROTO :DWORD,:DWORD,:DWORD,:DWORD

includelib kernel32.lib
includelib user32.lib

.data
    szText    db "Hello, world!",0
    szCaption db "Win32Asm",0

.code 
start: 
        push MB_OK
        lea eax,szCaption
        push eax
        lea eax,szText
        push eax
        push NULL
        call messageboxa
        xor eax,eax
        push eax
        call exitprocess
end start